/*
NAME
  revid - a testbed for re-muxing and re-directing video streams as MPEG-TS over various protocols.

DESCRIPTION
  See Readme.md

AUTHORS
  Alan Noble <anoble@gmail.com>
	Saxon A. Nelson-Milton <saxon.milton@gmail.com>

LICENSE
  revid is Copyright (C) 2017 Alan Noble.

  It is free software: you can redistribute it and/or modify them
  under the terms of the GNU General Public License as published by the
  Free Software Foundation, either version 3 of the License, or (at your
  option) any later version.

  It is distributed in the hope that it will be useful, but WITHOUT
  ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
 for more details.

  You should have received a copy of the GNU General Public License
  along with revid in gpl.txt.  If not, see [GNU licenses](http://www.gnu.org/licenses).
*/

// revid is a testbed for re-muxing and re-directing video streams as MPEG-TS over various protocols.
package revid

import (
	"bufio"
	"bytes"
	"errors"
	"fmt"
	"io"
	"io/ioutil"
	"net/http"
	"os"
	"os/exec"
	"strconv"
	"time"

	//"bitbucket.org/ausocean/av/parser"
	//"bitbucket.org/ausocean/av/tsgenerator"
	"../generator"
	"../parser"

	//"bitbucket.org/ausocean/av/ringbuffer"
	//"bitbucket.org/ausocean/utils/smartLogger"
	"../ringbuffer"
)

// Misc constants
const (
	clipDuration          = 1                   // s
	mp2tPacketSize        = 188                 // MPEG-TS packet size
	mp2tMaxPackets        = 2016 * clipDuration // # first multiple of 7 and 8 greater than 2000
	ringBufferSize        = 1000 / clipDuration
	ringBufferElementSize = 10000000
	maxClipSize           = 100000
	httpTimeOut           = 5 // s
	packetsPerFrame       = 7
	h264BufferSize        = 1000000
	bitrateTime           = 60
	mjpegParserInChanLen  = 100000
	ffmpegPath            = "/home/saxon/bin/ffmpeg"
)

// Log Types
const (
	Error   = "Error"
	Warning = "Warning"
	Info    = "Info"
	Debug   = "Debug"
)

// RevidInst provides methods to control a revidInst session; providing methods
// to start, stop and change the state of an instance using the Config struct.
type RevidInst interface {
	Start()
	Stop()
	ChangeState(newconfig Config) error
	GetConfigRef() *Config
	Log(logType, m string)
	IsRunning() bool
}

// The revidInst struct provides fields to describe the state of a RevidInst.
type revidInst struct {
	ffmpegPath  string
	tempDir     string
	ringBuffer  ringbuffer.RingBuffer
	config      Config
	isRunning   bool
	outputFile  *os.File
	inputFile   *os.File
	generator   generator.Generator
	parser      parser.Parser
	cmd         *exec.Cmd
	ffmpegCmd   *exec.Cmd
	inputReader *bufio.Reader
	ffmpegStdin io.WriteCloser
	outputChan  chan []byte
	setupInput  func() error
	setupOutput func() error
	getFrame    func() []byte
	flushData   func()
	sendClip func(clip []byte) error
}

// NewRevidInstance returns a pointer to a new revidInst with the desired
// configuration, and/or an error if construction of the new instant was not
// successful.
func NewRevidInstance(config Config) (r *revidInst, err error) {
	r = new(revidInst)
	r.ringBuffer = ringbuffer.NewRingBuffer(ringBufferSize, ringBufferElementSize)
	err = r.ChangeState(config)
	if err != nil {
		return nil, err
	}
	r.outputChan = make(chan []byte, 10000)
	r.parser.Start()
	go r.packClips()
	r.Log(Info, "New revid instance created! config is:")
	r.Log(Info, fmt.Sprintf("%v", r.config))
	return
}

// GetConfigRef returns a pointer to the revidInst's Config struct object
func (r *revidInst) GetConfigRef() *Config {
	return &r.config
}

// ChangeState swaps the current config of a revidInst with the passed
// configuration; checking validity and returning errors if not valid.
func (r *revidInst) ChangeState(config Config) error {
	r.config.Logger = config.Logger
	err := config.Validate(r)
	if err != nil {
		return errors.New("Config struct is bad!: " + err.Error())
	}
	r.config = config
	switch r.config.Output {
	case File:
		r.sendClip = r.sendClipToFile
		r.setupOutput = r.setupOutputForFile
	case Rtmp:
		r.setupOutput = r.setupOutputForRtmp
		r.sendClip = r.sendClipToRtmp
	case Http:
		r.sendClip = r.sendClipToHTTP
	}
	switch r.config.Input {
	case Raspivid:
		r.setupInput = r.setupInputForRaspivid
	case File:
		r.setupInput = r.setupInputForFile
	}
	switch r.config.InputCodec {
	case H264:
		r.Log(Info, "Using H264 parser!")
		r.parser = parser.NewH264Parser()
		fmt.Println("here")
	case Mjpeg:
		r.Log(Info, "Using MJPEG parser!")
		r.parser = parser.NewMJPEGParser(mjpegParserInChanLen)
	}
	if r.config.Packetization == None {
		r.parser.SetOutputChan(r.outputChan)
		r.getFrame = r.getFrameNoPacketization
	} else {
		switch r.config.Packetization {
		case Mpegts:
			frameRateAsInt, _ := strconv.Atoi(r.config.FrameRate)
			r.generator = generator.NewTsGenerator(uint(frameRateAsInt))
		case Flv:
			frameRateAsInt, _ := strconv.Atoi(r.config.FrameRate)
			r.generator = generator.NewFlvGenerator(false, true, uint(frameRateAsInt))
		}
		r.getFrame = r.getFramePacketization
		r.parser.SetOutputChan(r.generator.GetInputChan())
		r.generator.Start()
	}
	return nil
}

// Log takes a logtype and message and tries to send this information to the
// logger provided in the revidInst config - if there is one, otherwise the message
// is sent to stdout
func (r *revidInst) Log(logType, m string) {
	if r.config.Logger != nil {
		r.config.Logger.Log(logType, m)
	} else {
		fmt.Println(logType + ": " + m)
	}
}

// IsRunning returns true if the revidInst is currently running and false otherwise
func (r *revidInst) IsRunning() bool {
	return r.isRunning
}

// Start invokes a revidInst to start processing video from a defined input
// and packetising to a defined output.
func (r *revidInst) Start() {
	if r.isRunning {
		r.Log(Warning, "revidInst.Start() called but revid already running!")
		return
	}
	r.Log(Info, "Starting Revid!")
	r.setupOutput()
	r.setupInput()
	go r.outputClips()
	r.isRunning = true
}

// Stop halts any processing of video data from a camera or file
func (r *revidInst) Stop() {
	if r.isRunning {
		r.Log(Info, "Stopping revid!")
		r.isRunning = false
		if r.cmd != nil {
			r.cmd.Process.Kill()
		}
	} else {
		r.Log(Warning, "revidInst.Stop() called but revid not running!")
	}
}

// Start invokes a revidInst to start processing video from a defined input
// and packetising to a defined output.
func (r *revidInst) getFrameNoPacketization() []byte {
	return <-r.outputChan
}

// Start invokes a revidInst to start processing video from a defined input
// and packetising to a defined output.
func (r *revidInst) getFramePacketization() []byte {
	return <-(r.generator.GetOutputChan())
}

// Start invokes a revidInst to start processing video from a defined input
// and packetising to a defined output.
func (r *revidInst) flushDataNoPacketisation() {
	for len(r.outputChan) > 0 {
		<-(r.outputChan)
	}
}

// Start invokes a revidInst to start processing video from a defined input
func (r *revidInst) flushDataMpegtsPacketisation() {
	for len(r.generator.GetOutputChan()) > 0 {
		<-(r.generator.GetOutputChan())
	}
}

// packClips takes data segments; whether that be tsPackets or jpeg frames and
// packs them into clips 1s long.
func (r *revidInst) packClips() {
	clipSize := 0
	packetCount := 0
	for {
		if clip, err := r.ringBuffer.Get(); err != nil {
			r.Log(Error, err.Error())
			r.Log(Warning, "Clearing output chan!")
			r.flushData()
		} else {
			for {
				frame := r.getFrame()
				lenOfFrame := len(frame)
				upperBound := clipSize + lenOfFrame
				copy(clip[clipSize:upperBound], frame)
				packetCount++
				clipSize += lenOfFrame
				if packetCount >= r.config.FramesPerClip {
					if err := r.ringBuffer.DoneWriting(clipSize); err != nil {
						r.Log(Error, err.Error())
						r.Log(Warning, "Dropping clip!")
					}
					clipSize = 0
					packetCount = 0
					break
				}
			}
		}
	}
}

// outputClips takes the clips produced in the packClips method and outputs them
// to the desired output defined in the revidInst config
func (r *revidInst) outputClips() {
	now := time.Now()
	prevTime := now
	bytes := 0
	delay := 0
	for r.isRunning {
		// Here we slow things down as much as we can to decrease cpu usage
		switch {
		case r.ringBuffer.GetNoOfElements() < 2:
			delay++
			time.Sleep(time.Duration(delay) * time.Millisecond)
		case delay > 10:
			delay -= 10
		}
		// If the ringbuffer has something we can read and send off
		if clip, err := r.ringBuffer.Read(); err == nil {
			r.Log(Debug, fmt.Sprintf("Delay is: %v\n", delay))
			r.Log(Debug, fmt.Sprintf("Ring buffer size: %v\n", r.ringBuffer.GetNoOfElements()))
			// Output clip to the output specified in the configuration struct
			bytes += len(clip)
			for err := r.sendClip(clip); err != nil; {
				r.Log(Error, err.Error())
				r.Log(Warning, "Send failed trying again!")
				err = r.sendClip(clip)
			}
			if err := r.ringBuffer.DoneReading(); err != nil {
				r.Log(Error, err.Error())
			}
			// Log some information regarding bitrate and ring buffer size if it's time
			now = time.Now()
			deltaTime := now.Sub(prevTime)
			if deltaTime > time.Duration(bitrateTime)*time.Second {
				r.Log(Info, fmt.Sprintf("Bitrate: %v bits/s\n", int64(float64(bytes*8)/float64(deltaTime/1e9))))
				r.Log(Info, fmt.Sprintf("Ring buffer size: %v\n", r.ringBuffer.GetNoOfElements()))
				prevTime = now
				bytes = 0
			}
		} else {
			r.Log(Debug, err.Error())
			time.Sleep(1*time.Second)
		}
	}
}

// Start invokes a revidInst to start processing video from a defined input
// and packetising to a defined output.
func (r *revidInst) sendClipToFile(clip []byte) error {
	_,err := r.outputFile.Write(clip)
	if err != nil {
		return err
	}
	return nil
}

// sendClipToHTTP takes a clip and an output url and posts through http.
func (r *revidInst) sendClipToHTTP(clip []byte) error {
	timeout := time.Duration(httpTimeOut * time.Second)
	client := http.Client{
		Timeout: timeout,
	}
	url := r.config.HttpAddress+strconv.Itoa(len(clip))
	r.Log(Debug, fmt.Sprintf("Posting %s (%d bytes)\n", url, len(clip)))
	resp, err := client.Post(url, "video/mp2t", bytes.NewReader(clip)) // lighter than NewBuffer
	if err != nil {
		return fmt.Errorf("Error posting to %s: %s", url, err)
	}
	defer resp.Body.Close()
	body, err := ioutil.ReadAll(resp.Body)
	if err == nil {
		r.Log(Debug, fmt.Sprintf("%s\n", body))
	} else {
		r.Log(Error, err.Error())
	}
	return nil
}

// Start invokes a revidInst to start processing video from a defined input
// and packetising to a defined output.
func (r *revidInst) sendClipToRtmp(clip []byte) error {
	fmt.Println("Outputting!")
	_, err := r.ffmpegStdin.Write(clip)
	if err != nil {
		return err
	}
	return nil
}

// Start invokes a revidInst to start processing video from a defined input
// and packetising to a defined output.
func (r *revidInst) setupOutputForRtmp() error {
	r.ffmpegCmd = exec.Command(ffmpegPath,
		"-f", "h264",
		"-r", r.config.FrameRate,
		"-i", "-",
		"-f", "lavfi",
		"-i", "aevalsrc=0",
		"-fflags", "nobuffer",
		"-vcodec", "copy",
		"-acodec", "aac",
		"-map", "0:0",
		"-map", "1:0",
		"-strict", "experimental",
		"-f", "flv",
		r.config.RtmpUrl,
	)
	var err error
	r.ffmpegStdin, err = r.ffmpegCmd.StdinPipe()
	if err != nil {
		r.Log(Error, err.Error())
		r.Stop()
		return err
	}
	err = r.ffmpegCmd.Start()
	if err != nil {
		r.Log(Error, err.Error())
		r.Stop()
		return err
	}
	return nil
}

func (r *revidInst) setupOutputForFile() (err error) {
	r.outputFile, err = os.Create(r.config.OutputFileName)
	return
}

// Start invokes a revidInst to start processing video from a defined input
// and packetising to a defined output.
func (r *revidInst) setupInputForRaspivid() error {
	r.Log(Info, "Starting raspivid!")
	switch r.config.InputCodec {
	case H264:
		r.cmd = exec.Command("raspivid",
			"-cd", "H264",
			"-o", "-",
			"-n",
			"-t", r.config.Timeout,
			"-b", r.config.Bitrate,
			"-qp", r.config.Quantization,
			"-w", r.config.Width,
			"-h", r.config.Height,
			"-fps", r.config.FrameRate,
			"-ih",
			"-g", r.config.IntraRefreshPeriod,
		)
	case Mjpeg:
		r.cmd = exec.Command("raspivid",
			"-cd", "MJPEG",
			"-o", "-",
			"-n",
			"-t", r.config.Timeout,
			"-fps", r.config.FrameRate,
		)
	}
	stdout, _ := r.cmd.StdoutPipe()
	err := r.cmd.Start()
	r.inputReader = bufio.NewReader(stdout)
	if err != nil {
		r.Log(Error, err.Error())
		return err
	}
	go r.readCamera()
	return nil
}

// Start invokes a revidInst to start processing video from a defined input
func (r *revidInst) setupInputForFile() error {
	go r.readFile()
	return nil
}

// readCamera reads data from the defined camera while the revidInst is running.
func (r *revidInst) readCamera() {
	r.Log(Info, "Reading camera data!")
	for r.isRunning {
		data := make([]byte, 1)
		_, err := io.ReadFull(r.inputReader, data)
		switch {
		case err != nil && err.Error() == "EOF" && r.isRunning:
			r.Log(Error, "No data from camera!")
			time.Sleep(5 * time.Second)
		case err != nil && r.isRunning:
			r.Log(Error, err.Error())
		default:
			r.parser.GetInputChan() <- data[0]
		}
	}
	r.Log(Info, "Out of reading routine!")
}

// readFile reads data from the defined file while the revidInst is running.
func (r *revidInst) readFile() error {
	if len(r.parser.GetInputChan()) == 0 {
		var err error
		r.inputFile, err = os.Open(r.config.InputFileName)
		if err != nil {
			r.Log(Error, err.Error())
			r.Stop()
			return err
		}
		stats, err := r.inputFile.Stat()
		if err != nil {
			r.Log(Error, "Could not get input file stats!")
			r.Stop()
			return err
		}
		data := make([]byte, stats.Size())
		_, err = r.inputFile.Read(data)
		if err != nil {
			r.Log(Error, err.Error())
			r.Stop()
			return err
		}
		for i := range data {
			r.parser.GetInputChan() <- data[i]
		}
		r.inputFile.Close()
	}
	return nil
}